1. Technical Field
The present invention relates to an image forming device and an image forming method, which are provided to form a latent image by exposing a photoreceptor to light emitted by a light emitting element.
2. Related Art
Image forming devices have been proposed, which form a latent image on a photoreceptor by using an effect in which the potential of the photoreceptor is changed by exposure of the photoreceptor to light. For example, in an image forming device described in JP-A-2008-238633, an exposure head that has light emitting elements arranged in a predetermined direction faces a photoreceptor. The surface of the photoreceptor is irradiated with light emitted by the light emitting elements. The light forms spots on the surface of the photoreceptor. The potentials of portions (of the surface of the photoreceptor) that are irradiated with the light are changed. In this case, the potentials of the portions that correspond to a latent image to be formed are changed by the irradiation with the light so that the latent image is formed on the surface of the photoreceptor. The image forming device causes toner to be attached to the formed latent image so that the latent image is developed into a visible image.
The amount of the toner that is attached to the latent image for the development depends on the amount of the change in the potential of the surface of the photoreceptor. Thus, in order to form an excellent image, it is important to accurately control the amount of the change (due to the irradiation with the light emitted by the light emitting element) in the potential of the surface of the photoreceptor. When the amount of the change in the potential is significantly different from a predetermined amount of change, toner with an appropriate amount cannot be attached to the surface of the photoreceptor. As a result, the density of the image is largely different from an appropriate density, and a desired image cannot be formed.
However, a variation in the spectral distribution of each of the light emitting elements and spectral characteristics of the photoreceptor may cause a problem when the amount of the change in the potential of the photoreceptor is controlled. Since the manufacturing accuracy of the light emitting elements is limited, it is difficult to make the spectral distributions of all the manufactured light emitting elements the same. The spectral distributions of some of the light emitting elements may be shifted in the direction of the axis that indicates the wavelength of light emitted by the light emitting elements, or the shapes of the spectral distributions may be changed. On the other hand, the spectral sensitivity of the photoreceptor is not constant and is changed depending on the wavelength of light with which the photoreceptor is irradiated. When the spectral distributions of the light emitting elements vary, the sensitivity of the photoreceptor to the light emitted by the light emitting elements may also vary. As a result, the amounts of changes in the potentials of portions of the photoreceptor may vary. Thus, when the spectral distributions of the light emitting elements vary, the amounts of the changes in the potentials of the portions of the photoreceptor may vary. The amounts of the changes in the potentials of the portions of the photoreceptor may not be stabilized due to variations in the spectral distributions of the light emitting elements and variations in the spectral sensitivity of the photoreceptor. As a result, an excellent image may not be formed.